1. Field of the Invention
The present invention relates to a connector for dispensing liquid from a tank, and more particularly to such a connector of a tank made of a synthetic resin, wherein: the tank contains liquid such as a highly purified chemical in liquid form or the like therein; and, the connector is mounted on an upper surface of the tank.
2. Description of the Related Art
Heretofore, a conventional liquid dispensing mechanism 1, for example such as one shown in FIG. 10 for dispensing liquid from a tank 2 made of a synthetic resin has been used in the art. Such a conventional liquid dispensing mechanism 1 is constructed of: an inner lid 4; and, an annular cap 5 provided with a female screw portion through which both the inner lid 4 and the annular cap 5 are fixedly mounted on a mouth portion 3 of the tank 2. Formed in an upper surface of the inner lid 4 are: an externally threaded connecting mouth portion 6 which is connected with a pressurized gas supply means (shown in phantom lines in FIG. 10) for supplying a pressurized gas from the gas supply means to the tank 2 through the connecting mouth portion 6 in order to forcibly dispense the liquid contained in the tank 2 from this tank 2 to the outside; and, another externally threaded connecting mouth portion 7 which is connected with a liquid dispensing means (shown in phantom lines in FIG. 10) for dispensing the liquid contained in the tank 2 to the outside though the connecting mouth portion 7, wherein both the connecting mouth portions 6 and 7 extend upward from the upper surface of the inner lid 4, as viewed in FIG. 10. Further, fixedly mounted in the externally threaded connecting mouth portion 7 of the inner lid 4 is a siphon tube 8 which extends up to an inner bottom surface of the tank 2.
In this conventional liquid dispensing mechanism 1, since each of the externally threaded mouth portions 6, 7 extends upward from the upper surface of the inner lid 4, the loot of each of these mouth portions 6, 7 is most susceptible to failure when subjected to a heavy load applied to the mouth portions 6, 7 in a direction perpendicular to the longitudinal axis of each of the mouth portions 6, 7. When the roots of these mouth portions 6, 7 of the inner lid 4 are broken under such heavy load, leakage of the liquid (i.e., chemical) and the pressurized gas both contained in the tank 2 occurs. This is a problem inherent in the prior art.
In order to solve the above problem, the applicant of the subject Patent application has already proposed a liquid dispensing mechanism (shown in FIG. 11) in his previous Japanese Patent application Laid-Open No. 2000-146089, in which mechanism: an inner lid 11 is fixedly mounted on a neck portion of a liquid tank through a tightening cap; and, formed in the inner lid 11 are a pair of concave portions which are threaded to form a pair of female screw holes 12, 13. In this previous mechanism, as shown in FIG. 11, one 12 of the female screw holes 12, 13 of the inner lid 11 threadably receives therein a pressurized gas supply plug 14 in which a valve 18 is incorporated. This incorporated valve 18 is forcibly pushed upward to seat on its corresponding valve seat and therefore to close a pressurized gas supply opening 20 in a normal condition under the influence of a resilient force exerted by a compression coil spring 17. On the other hand, the other 13 of the female screw holes 12, 13 of the inner lid 11 threadably receives therein a liquid dispensing plug 14 in which a valve 30 is incorporated. This incorporated valve 30 is forcibly pushed upward to seat on its corresponding valve seat and therefore to close a liquid dispensing opening 32 in a normal condition under the influence of a resilient force exerted by a compression coil spring 28.
In the previous mechanism disclosed in the Japanese Patent application Laid-Open No. 2000-146089: since the plugs 14 and 15 are embedded in the female screw holes 12 and 13, respectively, and therefore protected from any lateral load without fail, there is no fear of leakage of the liquid and the pressurized gas from the tank even when the plugs 14, 15 are subjected to a lateral heavy load when the liquid contained in the tank is dispensed from the tank to the outside.
However, this previous one of the liquid dispensing mechanisms suffers from another problem as follows: since both the pressurized gas supply plug 14 and the liquid dispensing plug 15 of the liquid dispensing mechanism extend upward beyond the inner lid 11, each of these plugs 14, 15 constitutes a serious encumbrance to the liquid dispensing mechanism.